Experimental Investigation on a New Hybrid System Employing Wind-Driven DFIG and Solar PV Panels

Abstract

This paper investigates the operation of wind-driven doubly fed induction generator (DFIG) with solar photovoltaic (PV) system for supplying isolated loads. A simple control strategy has been developed to maintain a set voltage and frequency at the DFIG stator terminals which is envisaged as a virtual grid for supplying loads. This is achieved by effective closed-loop control of a PV-fed sinusoidal pulse width modulation (SPWM) inverter connected at the rotor terminals of DFIG. The DC link of the SPWM inverter is made as a stiff one by connecting a battery bank, which acts as an energy storage device as well as a contingency source when output of PV array is less. A boost converter is interfaced between solar PV panels and battery to enable maximum power extraction from PV panels. A single sensor-based maximum power point tracking (MPPT) algorithm has been developed for solar PV system. The MPPT algorithm monitors only the output current of the boost converter, as the output voltage of boost converter is held at a constant value by the battery bank. In order to demonstrate the successful working of the proposed hybrid system, a prototype has been fabricated in the laboratory and tested under different operating conditions.